Circuit breaker



R. C. BOYD CIRCUIT BREAKER Filed May 7, 1946 @8002 23 INVENTCR Fafierl C 505/0:

ATTORNEY Patented June 26, 1951 CIRCUIT BREAKER Robert C. Boyd, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 7, 1946, Serial No. 667,766

Claims. (01. 74483) This invention relates to circuit breakers, and more particularly to mechanism for interlocking two circuit breakers so as to prevent closing of either of the circuit breakers while the other is closed.

An object of the invention is to provide a pair of motor starting circuit breakers comprising a starting breaker and a runnin breaker with an improved interlock for enforcing the proper sequence of operation of the starting and running circuit breaker.

Another object of the invention is to provide an improved interlocking device for a pair of circuit breakers having means for providing a time interval following the opening of one of said circuit breakers during which time interval the other circuit breaker must be closed or be locked out.

Another object of the invention is to provide an interlock of the character described which is simple in design, of rugged construction and comprises but three main parts.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will best be understood from the following detailed description of a single embodiment thereof when read in conjunction with the accompanying drawing, in which:

Figure 1 is a sideelevational View of a pair of circuit breakers embodying the principles of the invention, one of the breakers being shown in the closed position and the other breaker being shown in the open position, and

Fig. 2 is an enlarged diagrammatic view partly in section taken substantially on line 11-11 of Fig. l and looking in the direction of the arrows.

Referring to Fig. 1 of the drawing, l l indicates a casing for housing a circuit breaker which may be of the oil or air break or of the gas blast type. Two casings II are provided for housing the starting and running breakers that are to be interlocked, the second casing being directly back of the casing ll illustrated which houses the starting breaker. The casings II are supported by means of brackets l3 (only one being shown) secured to a mounting frame by means of bolts I! only one of which is shown. A plurality of terminal connectors 59 are mounted on conducting rods 2| which extend through insulatin support members 23 into the casing H for each of the circuit breakers. Stationary contact means (not shown) are mounted on the lower ends of the rods 2! for each breaker. Movable contact 2 means (not shown) is provided for cooperating with the stationary contact means of each of the starting and running breakers.

The movable contact means for th starting and running breakers respectively are operated to open and close their respective circuits by means of levers 25 and 21 pivoted on a rod 29 supported in the brackets 13. The operating lever 25 for the starting breaker is manually operated by means of a starting handle 3i pivotally supported on a pin 33 mounted in a bracket 35. The bracket 35 is secured by suitable means to a front panel 3'! which is supported by means not shown on the frame l5. The handle 3! is connected by means of a linkage indicated generally at 39 to the starting-breaker operating lever 25. The linkage 39 comprises a lever 4| pivotally mounted on a pin 43 supported in an extension 45 of the bracket l3. One end of the lever 4| is connected to the handle 3! by means of an adjustable rod 41 and the other end of the lever 4| is connected by means of a link 29 to one end of a lever 5| having its other end connected by means of a link 53 to the operating lever 25 for the starting breaker. The lever 5! is mounted on a pivot pin supported in the bracket l3. The operating lever 2! for the running breaker is adapted to be operated by means of a handle 51, pivotally mounted on the pin 33 and operatively connected to the lever 21 by means of a linkage identical with the linkage 39 for the starting breaker. For the sake of clarity, the linkage for the running breaker has been omitted from the drawing.

Referring to Fig. 1 of the drawing, the starting breaker is shown in the open position and the running breaker is shown in the closed position.

In order to close the starting breaker, the handle 3| is moved in a counterclockwise direction from the open to the closed position. This movement of the starting handle acts through the connecting rod ll, the lever M and link 49 to rock the lever 5! in a counterclockwise direction, which through the link 53 moves the lever 25 also in counterclockwise or closing direction to close the starting breaker. Movement of the handle 3| in the opposite direction, that is, in a clockwise direction from the closed position to the open position reverses the movement of the linkage 39 and moves the operating lever 25 clockwise to open the starting breaker. The running breaker is operated to open and closed position in the same manner by operation of the running handle 51.

In operating certain types of motors, it is highly desirable first to connect the motor to a source of reduced voltage, and then, when the motor is running at the desired speed to connect it to a source of full voltage. This operation is usually effected by operating the starting and running circuit breakers in the proper sequence to first close the starting breaker, open the starting breaker and then close the running breaker. An important feature of the instant invention is the provision of interlocking means to enforce operation of the starting and running breakers in the proper sequence. It is also desirable that the running breaker be closed within a predetermined time interval following opening of the starting breaker. To this end means is provided to unlock the running breaker for a predetermined time interval when the starting handle is moved to open position. If the running breaker is not closed during the time interval, it will be again locked out.

The interlock mechanism (Fig. 2) comprises a lever 59 pivotally mounted on a pin 6! supported on the frame 55, a lever E3 pivotally mounted on a pin 65 also supported on the frame l5 and a connecting link i? pivotally connected at one end to the lever 59 at a point indicated at 69 above the pivot 6i of the lever. The other end of the link 67 is pivotally connected to the lever 63 at a point indicated at H below the pivot 55 of the lever 63. The lever 59 carries a mass of weight 13 which may be formed integral with the lever 59 or may be suitably secured thereto. The relation of the weight l3 to the pivot 55 of the lever 59 is such that it normally causes a projection 15 of the lever 59 to bear against the side of the handle 51 of the running breaker. In this position a locking shoulder ll of the lever 59 lies in the path of closing movement of the handle 5?, thus normally preventing closing the running breaker.

Referring to Fig. 2, the operating handles 3| and 51 respectively of the starting and running breakers are both shown in the open position and the closed position of the handles are indicated by dot and dash lines at 35' and 5'! respectively. With the breakers both in the open position the starting switch is closed by counterclockwise or downward movement of the handle 3! causes the opposite or right-hand end of the handle (Fig. l) to move upwardly. Early in the closing movement of the handle 3! it wipes by the lower rounded end of the lever 63 and moves this lever slightly in a clockwise direction. This movement is transmitted by the link 5'5 to the lever 59 and moves the latter slightly counterclockwise b'ut not a sufiicient distance to move the shoulder Ts out of the path of the running handle which consequently remains against closing movement. As soon as the handle SI for the starting breaker clears the lever 63, the weight '53 restores the interlock mechanism to the position shown in Fig. 2 wherein the running breaker is locked in open position. The closing movement of the handle 3! is then completed to close the starting breaker.

As soon as the motor has attained the proper speed, the starting breaker is opened by movement of the handle 3! from the closed to the open position and then the running breaker is immediately closed. Movement of the handle 3! to the open position moves the inner end thereof downwardly past the lever striking this lever a sharp blow. The force with which the handle 3| strikes the lever 63 starts the lever 59 and the weight it is unlocking direction with a sudden impulse and inertia causes the lever to swing far enough to unlock the running handle and provides a brief time interval during which the runwhich locked ning handle is moved to the closed position to close the running breaker. The weight 13 then causes the lever 59 to swing back past the locking position in which it appears in Fig. 2 which additional movement through the link 67 swings the lever E33 counterclockwise beyond the position shown to bring a beveled portion 79 directly above the starting handle 3|, thus preventing closing of the starting breaker while the running breaker is closed. In this position of the parts, the projection 55 rests against a limit stop 8| which prevents further movement of the lever 63 in counterclockwise direction. If the running handle 57 is not moved to the closed position during the time interval provided by the swinging movement of the weight 13, the weight causes the lever 59 to resume its locking position.

Movement of the running handle 5'! to the open position engages and moves the lever 59 in a counterclockwise direction which, through the link 6'? moves the lever 63 in a clockwise direction out or the path of closing movement of the starting handle 3! in preparation for a subsequent closing of the starting switch.

From the foregoing description, it will be apparent to those skilled in the art to which this invention appertains, that there is provided a simple and rugged mechanism for interlocking two circuit breakers to enforce a predetermined sequence of operation of the breakers, and also for providing a predetermined time interval following opening of one breaker during which the other breaker must be closed or be locked out.

Having described one embodiment of the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the particular embodiment disclosed without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given as reasonably broad interpretation as the prior art permits.

I claim as my invention:

1. The combination with a plurality of circuit breaker handles each independently movable to open and closed positions, of an interlock mechanism comprising a plurality of separate locking arms, there being a locking arm associated with each of said handles, means operatively relating said locking arms for simultaneous movement, one of said locking arms being moved in one direction by its associated handle when said handle is moved to open position to set the other locking arm in motion in th opposite direction to unlock the other handle, and means comprising an unbalanced mass disposed to be set in motion by said other locking arm and operable when set in motion to cause said other locking arm to complete its unlocking movement.

2. The combination with a plurality of circuit breaker handles each independently movable to open and closed positions, of an interlock mechanism comprising a plurality of separate locking arms there being a locking arm associated with each of said handles, means pivotally connecting said locking arms for simultaneous movement in opposite directions, one of said locking arms being operable by its associated handle when said handle is moved to open position to initiate movement of the other locking arm in unlocking direction, and means comprising an unbalanced mass disposed to be set in motion by said other locking arm and operable when set in motion to cause said other locking arm to complete its unlocking movement, said unbalanced mass maintaining said other locking arm in unlocking position for a predetermined time interval.

3. The combination with a; plurality of inde: pendently movable switch operating handles each movable between open and closed positions, of an interlock mechanism comprising a plurality of separate locking arms there being a locking arm associated with each of said handles, spaced pivots supporting said locking arms, means operatively relating said locking arms for simultaneous movement, one of said locking arms being movable in one direction by its associated handle when said handle is'moved to open position to initiate movement of the other locking arm in another direction to unlock said other handle, and means comprising an unbalanced mass operable by said other locking arm for causing said other locking arm to complete its unlocking movement, said unbalanced mass maintaining said other locking arm in unlocking position for a predetermined time interval and then returning said other locking arm to locking position.

4. The combination with a plurality of independently movable switch operating handles, each handle being movable between open and closed positions, of an interlock mechanism comprising a plurality of locking arms there being a locking arm associated with each of said handles, means pivotally connecting said locking arms for simultaneous movement in opposite directions, one of said locking arms being operable by its associated handle when said handle is moved to Open position to initiate movement of the other locking arm in unlocking direction, and means comprising an unbalanced mass set in motion by movement of said other locking arm in unlocking direction and operable when set in motion to cause said other locking arm to complete its unlocking movement, said unbalanced mass maintaining.

said locking arms out of locking position for a predetermined time interval and then moving said locking arms to a position wherein said one locking arm is in locking position.

5. The combination with a plurality of switchoperating handles independently movable to open and closed positions, of an interlock mechanism comprising a lever system having a pivoted lever associated with each of said handles for preventing movement of said handles to closed position, separate pivots for said levers, said pivoted levers being connected for movement in unison, one of said handles when moved to open position engaging its associated lever to initiate movement of said lever system to unlock said other handle, an unbalanced mass disposed to be set in motion by said lever system and operable when set in motion to complete the unlocking movement of said lever system.

6. The combination with a plurality of switchoperating handles independent-1y movable to open and closed positions, of an interlock mechanism comprising a lever system having a pivoted lever associated with each of said handles for preventing movement of said handles to closed position, separate pivots for said levers, means connecting said pivoted levers for movement in unison, one of said handles when moved to open position engaging its associated lever to initiate movement of said lever system to unlock said other handle, an unbalanced mass set in motion by movement of said lever system and operable when set in motion to complete the unlocking movement of said lever system, and said unbalanced mass providing a time interval during which said other handle is unlocked.

- 7. The combination with a plurality of switchoperating handles independently movable to open and closed positions, of an interlock mechanism comprising a lever system having a separate pivoted lever associated with each of said handles for preventing movement of said handles to closed position, means connecting said pivoted levers for simultaneous movement in opposite directions, one of said handles when moved to open position engaging its associated lever to initiate movement of said lever system to unlock said other handle, an unbalanced mass disposed to be set in motion by movement of one of said handles to open position and operable when set in motion to complete the unlocking movement of said lever system, and said unbalanced mass maintaining said lever system in unlocking position for a predetermined time interval and then moving said lever system past the position wherein it looks the other handle to a position wherein the one handle is prevented from movement to closed position.

8. The combination with a plurality of switchoperating handles independently movable between open to closed positions, of an interlockin mechanism comprising a lever system having a first lever normally in looking position for locking one of said handles in open position, a second lever normally in unlocking position, and means pivotally connecting said levers for simultaneous movement in opposite directions, the other of said handles when moved to open position engaging and starting said lever system in unlocking direction to move said first lever to unlocking position, and an unbalanced mass disposed to be set in motion by said first lever and operable when set in motion to cause said lever system to complete its unlocking movement and to maintain said lever system in unlocking condition for a predetermined time interval.

9. The combination with a plurality of switchoperating handles independently movable between open to closed positions, of an interlocking mechanism comprising a lever system having a first lever normally in looking position for locking one of said handles in open position and a second lever normally in unlocking position, separate pivot means for said levers, means pivotally connecting said first and second levers for simultaneous movement in opposite directions, the other of said handles when moved to open position engaging and starting said lever system in unlocking direction to move said first lever to unlocking position, and an unbalanced mass disposed to be set in motion by said first lever and operable when set in motion to cause said lever system to complete its unlocking movement and to maintain said lever system in unlocking condition for a predetermined time interval, and said unbalanced mass then moving said lever system to a position wherein said second lever is in looking position.

10. The combination with a plurality of switchoperating handles independently movable between open to closed positions, of an interlocking mechanism comprising a lever system having a first lever normally in looking position for looking one of said handles in open position and a second lever normally in unlocking position, spaced pivots for said levers, means connecting said first lever on one side of its pivot to said second lever on the opposite side of its pivot to cause simultaneous movement of said levers in 7 opposite directions, the other of said handles when moved to open position engaging said second lever and starting said lever system in unlocking direction to move said first lever to unlocking position, and an unbalanced mass connected to said first lever and set in motion by said first lever for causing said lever system to complete its unlocking movement and to maintain said lever system in unlocking condition for a predetermined time interval, and said unbalanced mass then moving said lever system to a position wherein said second lever is in looking position, and stop means for preventing movement of said first lever beyond locking position.

ROBERT C. BOYD.

8 REFERENCES CITED The following references are of record in'the file of this patent:

UNITED STATES PATENTS 2,262,071 Von Valkenburg Nov. 11, 1941 

